In DN 6, Otthadha asks the Buddha why he has seen heavenly sights but not heard heavenly sounds. The Buddha confirms that there are both heavenly sights and sounds. I have a guess what might be meant by heavenly sights, but what do you think is meant by heavenly sounds?

The devas' world (world of heavenly beings) is one realm among the six realms of existence (hell, hungry shades, animal, human, asuras, and devas). The beings there still communicate and some enjoy "heavenly" music just like us human enjoying our music (there's a special class of heavenly musicians called the Gandhabba). It's just that their world is too subtle for a human to see or to hear unless one's developed Divine Eye and Divine Ear capability (2 of the 6 supernormal powers). However the main message in DN 6 was about the Buddha cautioned the practitioner not to get attached to these powers while there're higher goals to be achieved, like cultivating the Noble Eightfold Path, attaining the Four Fruits and the end to all defilements..